A container handling apparatus usually comprises plural container handling units, which are arranged one after the other. Container handling units, for example, may be stretch-blow machines for manufacturing plastic containers (plastic bottles) from preforms. Furthermore, it is possible that the container handling unit is a labeling machine for labeling the containers. A further possibility of the container handling unit is a cleaning unit for cleaning the containers. To this is added a filling unit for filling the containers with a liquid or any other content, respectively. Eventually, a packaging unit for packaging or combining the containers to packs follows. Between the individual container handling units of a container handling apparatus plural transport means are provided. If a fault occurs at one of the container handling units, for example the labeling machine, the containers need to be buffered within the process. Through the buffering it is achieved that the container handling units upstream of the labeling unit can continue their operation, in order to transfer the containers only into the buffer of the transport means for buffering there, before supplying them to the labeling unit. Independently of the occurrence of a fault in a container handling apparatus it is also necessary to feed the containers to the individual container handling units of a container handling apparatus according to the step frequency of processing the containers in the individual container handling units. Therefore, it is necessary that the transport means, (buffer means) provided between the individual container handling units, can vary the buffering capacity depending on the required step frequency of the individual container handling units.
Canadian patent application CA 2 364 216 A1 discloses a transport system for the dynamical buffering of articles. The length of the transport system can be variably set, so that a certain number of containers can be buffered in the transport system. Thereunto a linear transport chain for transporting articles into the transport system and a second linear transport chain for transporting articles out of the transport system are provided. Between the first and the second linear transport chain plural U-shaped transport chains are provided, all of which are driven by one motor and thus are running at equal speeds. The bottom of the ‘U’ of each of these U-shaped transport chains is arranged at the side of the infeed of the containers into the transport system. The opening of the ‘U’ of each of these U-shaped transport chains is arranged at the side of the transport system opposite the infeed. The legs of the ‘U’ of the U-shaped transport chain are arranged parallel to the first and the second linear transport chain. Over the transport chains a transfer trolley is provided, which is displaceable along the transport chains. The transfer trolley exhibits a number of transfer discs equal to the number of U-shaped transport chains in the transport system. The transfer discs are positioned between linear transport segments of the transport chains. When articles reach one of the transfer discs of the transfer trolley from a transport chain, they are transferred to the next transport chain by the transport disc. The transport system is configured in such a way that linear transport segments, arranged parallel to each other, of all transport chains transport articles in opposite directions. Thus, the articles are transported back and forth in the transport system. By displacing the transfer system, moreover, the number of articles in the transport system, and thus the number of articles buffered there, can be set.
In the transport system described in CA 2 364 216 A1 all U-shaped chains have the same velocity. During the transfer of the containers from a transport chain to the transfer discs of the transfer trolley the containers are exposed to the risk of being damaged by collisions. Furthermore, there is the danger of a hand of a user getting between the transport chains during operation of the transport system or during maintenance work.
The company Nercon Eng. & Mfg., Inc., Oshkosh, Wis., USA, in U.S. Pat. No. 5,685,414, has described an endless transport system, in which the containers transported are not exposed to pressure from preceding containers. Furthermore, this company has developed a further transport system called “Flex Flow Accumulator”, in which the containers transported are exposed only to little pressure from preceding containers, and which, moreover, similar to the transport system of CA 2 364 216 A1, offers the possibility of buffering containers within the transport system. Therein also the number of containers that can be buffered in the transport system can be varied. Unlike CA 2 364 216 A1 a continuous chain is used for transporting the containers in the Flex Flow Accumulator. In this way it is intended to assure that there is no back pressure from the production line.
In the Flex Flow Accumulator by the company Nercon the containers therefore are on one transport chain during the entire transport. Therefore, on the one hand, all containers in the Flex Flow Accumulator are transported with an equal velocity. On the other hand with this construction the transport chain needs to be dimensioned relatively large, and thus is heavy. As such chains become more expensive with increasing dimensions, and because a heavy chain requires a greater driving force, the Flex Flow Accumulator by the company Nercon is relatively expensive with respect to production costs as well as operational costs.